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Portions of the grassland around the Rocky Flats installation of the U.S. Department of Energy, located about 12 km northwest of the Denver metropolitan area, were contaminated with Pu between 1959 and 1964. This study was designed to elucidate the Pu distribution patterns in the terrestrial ecosystem immediately downwind of the contamination source. We concluded that wind erosion of contaminated soil was likely the chief mechanism of plutonium transport and that soil contained 99.7% of the plutonium in the system. Plant and small animal compartments combined contained less than 0.3% of the total Pu inventory which averaged about 53 µCi/m2in the study area.

The extreme ecological degradation anticipated following a nuclear attack has resulted in public concern as to long-term environmental impacts of such an event. The general scientific community and public are unaware that over the years various groups and individuals have given serious thought to this matter. Such unawareness can probably be attributed to the limited distribution of reports and publication in obscure places. We have prepared this documentation of deliberations on ecological impacts of ionizing radiation resulting from nuclear war in order to familiarize interested persons with the available literature. It was not our objective to evaluate conclusions reported.

The potential for intrusion of soil‐covered uranium mill tailings was investigated with respect to two sciurids, the whitetail prairie dog (Cynomys leucurus) and the Wyoming ground squirrel (Spermophilus elegans). At a study site in Wyoming, measurements of gross alpha radioactivity on mound surfaces of artificially‐introduced prairie dogs were made to reveal any tailings penetration through 0.5 m of soil‐cover. Also, the impact of prairie dog burrowing upon radon flux from the cover surface was investigated. Limited, short‐lived intrusion of the waste layer was noted, but no significant changes in radon flux were detected. Wyoming ground squirrels confined to soil‐ and soil/tailings‐filled barrels burrowed to less extreme depths when confronted by mill tailings. Additional work at an inactive railings pile in western Colorado revealed repeated intrusion through a shallow cover and subsequent transport of radioactive material to the ground surface by prairie dogs that had voluntarily invaded the site at least 10 yr prior to this study. Radon flux from burrow entrances was significantly greater than that from undisturbed ground at the Colorado site. Differences in burrowing and radionuclide release between the Wyoming and Colorado sites may have been due to railings characteristics such as pH and/or texture, or to other factors such as residence time of the animals.

Concentrations of 137Cs and 90Sr were measured in trout from 51 mountain lakes in Colorado during the period 1965–1970. 137Cs levels ranged from 116 to 5802 pCi/kg wet muscle while 90Sr values ranged from 6 to 238 pCi/g bone ash. A yearly decrease in 137Cs levels was observed with the rate of decrease becoming smaller through the sampling period. The temporal trend was fit by a model employing a fallout “rate” factor and a “cumulative deposition” factor. Radionuclide concentrations generally were higher at the more northerly latitudes. Trout from lakes in certain watersheds were much higher in 137Cs than trout from other regions. Trout from montane and alpine lakes contained much more 137Cs and 90Sr than fish from waters at lower elevations. Dissolved calcium was significantly related to 90Sr values in trout, but potassium had no demonstrable effect on 137Cs values. A trophic relationship of 3.26 was found for 137Cs between large trout and small trout which presumably were the prey. General lake characteristics associated with relatively high 137Cs and 90Sr burdens in trout are described.